what are Благодарности for???? and If u get them what are they used for??

They're there so Ты can brag about it.
It can serve as a memory and such. It rewards a person so they know they are doing a great job contributing to Fanpop. That is, if Благодарности are used correctly.

Ты don't use them for anything. Ты just get them if someone like your pic или Комментарий или something like that... или in competitions :D